Spexin Promotes the Proliferation and Differentiation of C2C12 Cells In Vitro-The Effect of Exercise on SPX and SPX Receptor Expression in Skeletal Muscle In Vivo.

SPX (spexin) and its receptors GalR2 and GalR3 (galanin receptor subtype 2 and galanin receptor subtype 3) play an important role in the regulation of lipid and carbohydrate metabolism in human and animal fat tissue. However, little is still known about the role of this peptide in the metabolism of muscle. The aim of this study was to determine the impact of SPX on the metabolism, proliferation and differentiation of the skeletal muscle cell line C2C12. Moreover, we determined the effect of exercise on the SPX transduction pathway in mice skeletal muscle. We found that increased SPX, acting via GalR2 and GalR3 receptors, and ERK1/2 phosphorylation stimulated the proliferation of C2C12 cells (p < 0.01). We also noted that SPX stimulated the differentiation of C2C12 by increasing mRNA and protein levels of differentiation markers Myh, myogenin and MyoD (p < 0.01). SPX consequently promoted myoblast fusion into the myotubule (p < 0.01). Moreover, we found that, in the first stage (after 2 days) of myocyte differentiation, GalR2 and GalR3 were involved, whereas in the last stage (day six), the effect of SPX was mediated by the GalR3 isoform. We also noted that exercise stimulated SPX and GalR2 expression in mice skeletal muscle as well as an increase in SPX concentration in blood serum. These new insights may contribute to a better understanding of the role of SPX in the metabolism of skeletal muscle.

Modulatory effects of chitosan adipate on the T and B lymphocyte subsets in mice.

This study examined the subsets of T lymphocytes in the thymus, spleen and mesenteric lymph nodes as well as the subsets of B lymphocytes in the spleen and mesenteric lymph nodes in mice administered chitosan adipate (20 mg/kg) intraperitoneally once or four times at 24 h intervals. The results showed that chitosan adipate decreased the percentage of immature CD4+CD8+ thymic T cells and increased the percentage of mature CD4+ and CD8+ thymocytes. The most significant stimulating effect was observed after four injections. A single exposure to chitosan adipate increased the percentage of CD4+ mesenteric lymph node cells, but four injections of the drug increased the percentage of CD4+ and CD8+ mesenteric lymph node cells. Chitosan adipate had no effect on the subset of splenic T cells. In contrast, chitosan adipate administered either once or four times increased the percentage of CD19+ splenocytes but had no effect on the percentage of CD19+ mesenteric lymph node cells. Overall, chitosan adipate induces the maturation and differentiation of thymocytes, and regulates the number of B splenic cells and lymph node T cells irrespective of the number of doses.

Modulation of cellular immune response by orbifloxacin in noninfected and E. coli-infected mice.

The studies were conducted on noninfected and Escherichia (E) coli-infected mice treated with orbifloxacin administered orally 10 times at 24-hr intervals at a dose of 2.5 mg/kg. Orbifloxacin did not change the activity of peritoneal macrophages in noninfected mice. Administration of orbifloxacin in E. coli-infected mice modulated the effects of infection on the percentage of phagocyting macrophages, the percentage of NBT-positive cells, and nitric oxide production. Orbifloxacin did not affect the synthesis and release of interleukin-1 by macrophages. Orbifloxacin exerted a modulating effect on the subsets of lymphocytes in thymus, spleen, and mesenteric lymph node cells in noninfected and E. coli-infected mice.